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Definition

Cluster headaches occur in cyclical patterns or clusters, which gives the condition its name. Cluster headache is one of the most painful types of headache.

Cluster headache commonly awakens you in the middle of the night with intense pain in or around one eye on one side of your head.

Bouts of frequent attacks, known as cluster periods, may last from weeks to months, usually followed by remission periods when the headache attacks stop completely. During remission, no headaches occur for months and sometimes even years.

Fortunately, cluster headache is rare and not life-threatening. Treatments can help make cluster headache attacks shorter and less severe. In addition, medications can help reduce the number of cluster headaches.

Symptoms

Common signs and symptomsA cluster headache strikes quickly, usually without warning. Common signs and symptoms include:

Excruciating pain, generally located in or around one eye, but may radiate to other areas of your face, head, neck and shoulders

One-sided pain

Restlessness

Excessive tearing

Redness in your eye on the affected side

Stuffy or runny nasal passage in your nostril on the affected side of your face

Sweaty, pale skin (pallor) on your face

Swelling around your eye on the affected side of your face

Drooping eyelid

The pain of a cluster headache is often described as sharp, penetrating or burning. People with this condition say that the pain feels like a hot poker being stuck in the eye or that the eye is being pushed out of its socket.

People with cluster headache appear restless. They may pace or sit through the attack. In contrast to people with migraine, people with cluster headache usually avoid lying down during an attack because this position seems to increase the pain.

Some migraine-like symptoms — including nausea, sensitivity to light and sound, and aura — may occur with a cluster headache, though usually on one side.

Cluster period characteristicsA cluster period generally lasts from six to 12 weeks. The starting date and the duration of each cluster period may be consistent from period to period. For example, cluster periods may occur seasonally, such as every spring or every fall.

Most people have episodic cluster headaches. In episodic cluster headaches, the cluster headaches occur for one week to a year, followed by a pain-free remission period that may last as long as 12 months before another cluster headache develops.

Chronic cluster periods may continue for more than a year, or pain-free periods may last less than one month.

During a cluster period:

Headaches usually occur every day, sometimes several times a day.

A single attack may last from 15 minutes to three hours.

The attacks often happen at the same time within each 24-hour day.

The majority of attacks occur at night, usually one to two hours after you go to bed.

The pain usually ends as suddenly as it begins, with rapidly decreasing intensity. After attacks, most people are completely free from pain, but exhausted.

When to see a doctorSee your doctor if you've just started to experience cluster headaches to rule out other disorders and to find the most effective treatment.

Headache pain, even when severe, usually isn't the result of an underlying disease, but headaches may occasionally indicate a serious underlying medical condition, such as a brain tumor or rupture of a weakened blood vessel (aneurysm).

Additionally, if you have a history of headaches, see your doctor if the pattern changes or your headaches suddenly feel different.

Seek emergency care if you have any of these signs and symptoms:

Abrupt, severe headache, often like a thunderclap

Headache with a fever, nausea or vomiting, stiff neck, mental confusion, seizures, numbness, or speaking difficulties, which may indicate a number of problems, including stroke, meningitis, encephalitis or brain tumor

Headache after a head injury, even if it's a minor fall or bump, especially if it gets worse

A sudden, severe headache unlike any other headache you've experienced

Headache that gets progressively worse over days and changes in pattern

Causes

The exact cause of cluster headaches is unknown, but abnormalities in the hypothalamus likely play a role. Cluster attacks usually occur with clocklike regularity during a 24-hour day, and the cycle of cluster periods often follows the seasons of the year.

These patterns suggest that the body's biological clock is involved. In humans, the biological clock is located in the hypothalamus, which lies deep in the center of your brain.

Abnormalities of the hypothalamus may explain the timing and cyclical nature of cluster headache. Imaging studies have detected increased activity in the hypothalamus during the course of a cluster headache.

Unlike migraine and tension headache, cluster headache generally isn't associated with triggers, such as foods, hormonal changes or stress. Some people experience an aura or nausea similar to those experienced with migraine headaches.

Once a cluster period begins, however, consumption of alcohol can quickly trigger a splitting headache. For this reason, many people with cluster headache avoid alcohol for the duration of a cluster period.

Other possible triggers include the use of medications such as nitroglycerin, a drug used to treat heart disease.

Preparing for your appointment

You're likely to start by seeing your family doctor. However, you may be referred to a neurologist, a doctor trained in treating brain and nervous system disorders, such as headache.

Because appointments can be brief, and there's often a lot to talk about, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, as well as what to expect from your doctor.

Keep a headache diaryOne of the most helpful things you can do is keep a headache diary. Each time you get a headache, jot down these details that may help your doctor diagnose your particular kind of headache and discover possible headache triggers.

Date. Charting the date and time of each headache can help you recognize patterns.

Duration. How long did your headache last?

Intensity. Rate your headache pain on a scale from 1 to 10, with 10 being the most severe.

Triggers. List possible triggers that may have caused your headache, such as certain foods, sounds, odors, physical activity or oversleeping.

Symptoms. Did you experience any preceding symptoms?

Medications. What medications have you taken? List any, including dosages, even if they're unrelated to your headache.

Relief. Have you experienced any pain relief, from complete pain relief to none?

Your time with your doctor is limited, so preparing a list of questions may help you make the most of your time together. List your questions from most important to least important in case time runs out. For cluster headaches, some basic questions to ask your doctor include:

What's the most likely cause of my symptoms?

Are there other possible causes for my symptoms?

What kinds of tests do I need? What will these tests rule out?

Is my condition likely temporary or chronic?

What treatments are available? Which do you recommend?

What are the alternatives to the primary approach that you're suggesting?

I have other health conditions. How can I best manage them together?

Are there any restrictions that I need to follow?

Do I need to see a specialist?

Is there a generic alternative to the medicine you're prescribing?

What are common side effects to the medications you're prescribing?

Are there any brochures or other printed material that I can take home with me? What websites do you recommend?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctorYour doctor will likely ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on later. Your doctor may ask:

When did you begin experiencing symptoms?

Have your symptoms been continuous or occasional?

Do your symptoms tend to occur at the same time of day? Do they occur during the same season each year?

Tests and diagnosis

Cluster headache has a characteristic type of pain and pattern of attacks. A diagnosis depends on your description of the attacks, including your pain, the location and severity of your headaches, and associated symptoms. The frequency and duration of your headaches also are important factors.

If you have chronic or recurrent headaches, your doctor may try to pinpoint the type and cause of your headache using certain approaches.

Neurological examinationA neurological examination may help your doctor detect physical signs of a cluster headache. Sometimes the pupil of your eye may appear smaller, or your eyelid may droop, even between attacks.

Imaging testsIf you have unusual or complicated headaches or an abnormal neurological examination, your doctor may recommend other tests to rule out other serious causes of head pain, such as a tumor or aneurysm. Common brain imaging tests include:

Computerized tomography (CT) scan. A CT scan uses a series of X-rays to create detailed cross-sectional images of your brain.

Magnetic resonance imaging (MRI). An MRI uses a powerful magnetic field and radio waves to produce detailed images of your brain and blood vessels.

Treatments and drugs

There's no cure for cluster headaches. The goal of treatment is to decrease the severity of pain, shorten the headache period and prevent the attacks.

Because the pain of a cluster headache comes on suddenly and may subside within a short time, cluster headache can be difficult to evaluate and treat, as it requires fast-acting medications.

Some types of acute medication can provide some pain relief quickly. Based on the latest studies, the therapies listed below have proved to be most effective for acute and preventive treatment of cluster headache.

Oxygen. Briefly inhaling 100 percent oxygen through a mask at a minimum rate of at least 12 liters a minute provides dramatic relief for most who use it. The effects of this safe, inexpensive procedure can be felt within 15 minutes.

The major drawback of oxygen is the need to carry an oxygen cylinder and regulator with you, which can make the treatment inconvenient and inaccessible at times. Small, portable units are available, but some people still find them impractical.

Triptans. The injectable form of sumatriptan (Imitrex), which is commonly used to treat migraine, is also an effective treatment for acute cluster headache.

The first injection may be given while under medical observation. Some people may benefit from using sumatriptan in nasal spray form, but for most people this isn't as effective as an injection and it may take longer to work. Sumatriptan isn't recommended if you have uncontrolled high blood pressure or heart disease.

Another triptan medication, zolmitriptan (Zomig), can be taken in nasal spray or tablet form for relief of cluster headache. This medication may be an option if you can't tolerate other forms of fast-acting treatments.

Octreotide. Octreotide (Sandostatin), an injectable synthetic version of the brain hormone somatostatin, is an effective treatment for cluster headache.

Local anesthetics. The numbing effect of local anesthetics, such as lidocaine (Xylocaine), may be effective against cluster headache pain in some people when given through the nose (intranasal).

Dihydroergotamine. The intravenous form of dihydroergotamine (D.H.E. 45) may be an effective pain reliever for some people with cluster headache. This medication is also available in an inhaled (intranasal) form called Migranal, but this form hasn't been proved to be effective.

To have the medication administered through a vein (intravenously), you'll need to go to a hospital or doctor's office to have the medication administered through a vein (intravenously).

Preventive treatmentsPreventive therapy starts at the onset of the cluster episode with the goal of suppressing attacks.

Determining which medicine to use often depends on the length and regularity of your episodes. Under the guidance of your doctor, the drugs can be tapered off once the expected length of the cluster episode ends.

Calcium channel blockers. The calcium channel blocking agent verapamil (Calan, Verelan, others) is often the first choice for preventing cluster headache. Verapamil is often used in conjunction with other medications. Occasionally, longer term use is needed to manage chronic cluster headache.

Side effects may include constipation, nausea, fatigue, swelling of the ankles and low blood pressure.

Corticosteroids. Inflammation-suppressing drugs called corticosteroids, such as prednisone, are fast-acting preventive medications that may be effective for many people with cluster headaches.

Your doctor may prescribe corticosteroids if your cluster headache condition has only recently started or if you have a pattern of brief cluster periods and long remissions.

Although corticosteroids may often be a good short-term option, serious side effects such as diabetes, hypertension and cataracts make them inappropriate for long-term use.

Lithium carbonate. Lithium carbonate, which is used to treat bipolar disorder, may be effective in preventing chronic cluster headache if other medications haven't prevented cluster headaches.

Side effects include tremor, increased thirst and diarrhea. Your doctor can adjust the dosage to minimize side effects.

While you're taking this medication, your blood will be checked regularly for the development of more-serious side effects, such as kidney damage.

Nerve block. Injecting a numbing agent (anesthetic) and corticosteroid into the area around the occipital nerve, located at the back of your head, may help improve chronic cluster headaches.

An occipital nerve block may be useful for temporary relief until long-term preventive medications take effect.

Ergots. Ergotamine, available as a tablet that you place under your tongue, can be taken before bed to prevent nighttime attacks.

Self-injected dihydroergotamine (D.H.E. 45) also may be helpful. Ergot medications may be effective if taken early in your cluster attacks, but they can't be combined with triptans and can only be used for brief periods of time.

Melatonin. Studies show that 10 milligrams of melatonin taken in the evening might reduce the frequency of cluster headache.

Other preventive medications used for cluster headache include anti-seizure medications such as divalproex (Depakote) and topiramate (Topamax).

SurgeryRarely, doctors may recommend surgery for people with chronic cluster headache who don't find relief with aggressive treatment or who can't tolerate the medications or their side effects.

Surgical procedures for cluster headache attempt to damage the nerve pathways thought to be responsible for pain, most commonly the trigeminal nerve that serves the area behind and around your eye.

However, the long-term benefits of surgery are disputed. Also, because of the possible complications — including muscle weakness in your jaw or sensory loss in certain areas of your face and head — it's rarely considered.

Research in potential cluster headache treatmentsAs scientists learn more about the causes of cluster headache, they're able to develop more-selective treatments for the condition.

Researchers are studying a potential treatment called occipital nerve stimulation. In this procedure, your surgeon implants electrodes in the back of your head and connects them to a small pacemaker-like device (generator). The electrodes send impulses to stimulate the area of the occipital nerve, which may block or relieve your pain signals.

Several small studies of occipital nerve stimulation found that the procedure reduced pain in some people with chronic cluster headaches.

Similar research is underway with deep brain stimulation. In this procedure, doctors implant an electrode in the hypothalamus, the area of your brain associated with the timing of cluster periods. Your surgeon connects the electrode to a generator that changes your brain's electrical impulses and may help relieve your pain.

Deep brain stimulation of the hypothalamus may provide relief for people with severe, chronic cluster headaches that haven't been successfully treated with other medications.

Researchers are studying other types of brain and nerve stimulation to prevent and treat cluster headaches.

Alternative medicine

Because cluster headaches can be so painful, you may be tempted to try alternative or complementary therapies to relieve your pain.

A survey of people with cluster headache who tried a number of alternative therapies — including acupuncture, acupressure, therapeutic touch, chiropractic and homeopathy — found that fewer than 10 percent thought these therapies effective.

Some natural medicines may be worth a try, however. In one study, extract from kudzu, a vine species originally found in Asian countries, was shown to alleviate the intensity, frequency and duration of cluster headache attacks. However, kudzu extract didn't decrease the length of the cluster cycle.

Melatonin also has shown modest effectiveness in treating nighttime attacks.

Coping and support

Living with cluster headache can be very difficult. Cluster headaches can be frightening to you and to your family and friends. The debilitating attacks may seem unbearable.

In addition to the physical symptoms, the chronic pain that often accompanies cluster headache attacks can make you anxious or depressed. Ultimately, it may affect your interaction with friends and family, your productivity at work, and the overall quality of your life.

Talking to a counselor or therapist can help you cope with the effects of cluster headache. Or you may find encouragement and understanding in a headache support group. Although support groups aren't for everyone, they can be good sources of information.

You may also find support groups are a good place for you to share your experiences and hear other group members' experiences. If you're interested, your doctor may be able to recommend a group in your area.

Prevention

Because the cause of cluster headache is unknown, you can't prevent a first occurrence. However, a preventive strategy is crucial for managing cluster headache because only trying to treat acute attacks with medications can seem hopeless.

Prevention can help reduce the frequency and severity of the cluster attacks and the risk of medication overuse headaches. Preventive medications can also increase the effectiveness of acute medications.

In addition, you may help reduce your risk of future attacks by avoiding alcohol and nicotine, which often cause cluster headaches.